The present invention relates to an optical magnetometer able to detect weak magnetic fields of approximately 10.sup.-5 A/m.
It is known to measure the rotation of the polarization plane of linear polarized light supplied by a laser on traversing a magnetooptical medium subject to a magnetic field. This rotation, known as a Faraday rotation, is a function of the value of the component of the magnetic field parallel to the propagation direction, which makes it possible to obtain a field measurement by measuring said rotation.